The field of the present disclosure relates generally to required navigation performance (RNP) procedures and, more specifically, to RNP procedures including offset runway approach vectors for incoming aircraft.
Required Navigation Performance refers generally to a performance-based navigation (PBN) procedure including navigation containment and monitoring. An RNP system allows an aircraft navigation system to monitor its achieved navigation performance, and to identify whether operational requirements are being met during operation. RNP capability of an aircraft is a major component in determining separation criteria between an aircraft in flight and foreign objects to ensure that target levels of safety are met. For example, when implementing an RNP procedure, the aircraft must be qualified and capable of flying with an actual navigation precision equal to, or greater than, a required navigation performance prescribed by the procedure.
Aircraft using RNP procedures are required to navigate themselves accurately in accordance with a predetermined procedure. RNP procedures are now mandatory for certain difficult to navigate, terrain-challenged airports, such as those in Tibet, in Alaska, and in very high-altitude mountainous areas in South America. Some of these known airports have no direct approach vectors. Rather, the airports only have approach vectors with mountainous terrain on both sides such that the aircraft must be precisely maneuvered to navigate these approaches.
Aircraft manufacturers and operators have been exploring the application of RNP to runway approach vectors for use with other more easily navigable airports to facilitate ensuring target levels of safety are met for nearby approaching aircraft. For example, one such air traffic control procedure implementing RNP runway approach vectors is referred to as a “trombone” approach pattern. The trombone approach pattern includes routing approaching aircraft along the same downwind leg, and routing each of the approaching aircraft along differing radius-to-fix base legs towards a runway, which facilitates separating each aircraft at safe distances. However, when multiple approaching aircraft are traveling along the downwind leg substantially simultaneously, it may be difficult for an air traffic controller to determine whether each aircraft will eventually follow its designated base leg route.